Protractor.



A. FERRARIS.

PROTBAGTOR.

APPLICATION FILED SEPT. 9, 1913.

Patented Feb. 17, 1914.

IIIm

COLUMBIA PLANOGRAPH CO..WASHINGTON. 0. c.

ANTHONY FERRARIS, OF BRIDGEPORT, CONNECTICUT.

PROTRAOTOR.

Specification of Letters Patent.

Application filed September 9, 1913.

Patented Feb. 17, 1914. Serial No. 788,873.

To all whom it may concern Be it known that I, ANTHONY F nnnanrs, a citizen of the United States, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented new and useful Improvements in Protractors, of which the following is a specification.

The invention relates to a protractor designed primarily for use in laying off work.

The main object of the present invention is the provision of a protractor having a movable member serving as a scribing guide, which member is adapted for rotative movement about a center and which center has fixed relation with the center of the object on which the-laying out is contemplated, the member being adapted to be fixed in any desired position with relation to the protractor scale.

The invention in its preferred form of details will be described in the following specification, reference being had particularly to the accompanying drawings, in which Figure l is a plan of the protractor. Fig. 2 is an edge view. F igs. 3 and 4 are sections 011 lines 33 and 4-l respectively of Fig. 1.

Referring particularly to the accompanying drawings, the improved protractor is shown to include a scale plate 1, the same of usual protractor form having a semi-circular scale edge 2 preferably inscribed to indicate from 1 to 180 and a cross or diametric bar 3, the latter being centrally formed with an offset el havingan opening 5, the center of which opening is the center of the semi-circular edge. Inwardly of the scale margin is presented a plane portion 6 to form a guide.

Rotatably mounted in the opening 5 is a bushing 7 the latter having a shoulder fitting against the bottom of the opening wall, the latter being preferably partly enlarged as at 8 to receive the shouldered portion of the bushing. The bushing is intcriorly threaded at 9 to receive a centering screw 10, said screw having a milled head 11 at one end and point 152 at the opposite end. A gaging arm 18 is arranged to cooperate with the bushing being formed at one end with an opening 141' to fit snugly over the upper projecting end of the bushing, the opening 14: being formed in the relatively reduced portion of the arm and in such relation to the arm that one edge thereof will directly aline or radiate from the center of the ln'otractor. A clamping nut 15 is designed to cooperate with the screw 10 so that it may be moved down to clamp the arm against further movement with respect to the scale member. The free end of the arm is provided with an offset section 16 to bear upon the plane portion 6 of the scale edge, with the pointed end 17 to cooperate with the scale marks. A finger piece 18 is secured in the arm adjacent the free end to provide for moving the arm. In laying off a particular piece of work, the center of such work is found and the point of the screw seated therein, The arm is then adjusted with relation to the scale, in accordance with the particular lines of division required, clamped in place so as to fix it with relation to the scale, and. used as a scribing edge for laying off the work.

lVhat is claimed is:

1. A dividing protractor including a scale member having a degree scale, a bushing rotatably mounted in said member, a centering screw having threaded connection with the bushing, an arm rotatably mounted on the bushing and having a pointed end to cooperate with the scale and a clamp nut cooperating with the screw to secure the arm in fixed relation to the scale member.

2. A protractor including a scale member having a circular scale edge, a bushing rotatably mounted in said. member at the center about which the scale edge is formed, a centering screw having threaded conncction with the bushing and terminating in a centering point, an arm rotatably mounted on the bushing and having a pointed end to cooperate with the scale and. a clamp nut cooperating with the screw to fiX the arm with relation to the scale.

3. A protractor including a scale member having a circular scale edge, a bushing rotatably mounted. in said member at the center about which the scale edge is forn'led a centering screw having threaded connection with the bushing and terminating in a centering point, an arm rotatably mounted on the bushing and having a pointed end to 00- In testimony whereof I {mix my signature operate wlth the scale, and a clamp nut 00- 111 presence of two Witnesses. operetmg wlth the screw to fix the arm Wlth ANTHONY FERRARIS.

edge in radial ahnement With the center SAM BATEMAN,

I relatlon t0 the scale, sald arm havmg one Wltnessesz about which the scale edge is formed. WM. T. MULLINS.

Copies of this patent may be obtained for five cents each, by addressing the Gommiuioner oi E atentm Wazhington, D. G. 

